1. Field of the Invention
The present invention relates to a reciprocating electric shaver for shaving face whiskers (“hair”) by causing an inner cutter to move reciprocally while being pressed against the inner surface of an outer cutter that is substantially inverted-U-shaped when viewed from the side.
2. Description of the Related Art
Reciprocating electric shavers are commonly known. Generally, reciprocating electric shavers are made so that an inner cutter is caused to move reciprocally while it is being pressed against the inner surface of an outer cutter that is substantially inverted-U-shaped when seen from the side, and hair coming through the slits provided in the outer cutter is cut by the reciprocating inner cutter.
In the reciprocating electric shaver disclosed in Japanese Patent Application No. 2004-340838 (Japanese Patent Application Laid-Open (Kokai) No. 2006-149445), an outer cutter is held so that it can slide freely up and down in an outer cutter frame secured to a shaver main body that contains a motor, and an inner cutter, which is urged upward by an inner cutter upwardly pushing spring, is caused to move reciprocally while being pressed against the inner surface of the outer cutter. More specifically, in this shaver, an oscillator is employed, and this oscillator is vibrated by the motor housed in the shaver main body; in addition, the inner cutter is provided on this oscillator so that it is capable of swinging and is urged upward by an inner cutter upwardly pushing spring. The inner cutter is moved reciprocally while being pressed against the inner surface of the outer cutter by a prescribed spring force.
In this conventional shaver, the contact pressure of the outer cutter against the skin (hereinafter called the outer cutter float pressure) is set by the upward pushing force of the inner cutter, that is, by the spring force of the inner cutter upwardly pushing spring. Accordingly, the outer cutter, when contact is made against the skin with a force stronger than the spring force of the inner cutter upwardly pushing spring, will sink in (or descend) while compressing the inner cutter upwardly pushing spring.
The ideal pressure (float pressure) when the outer cutter sinks in varies depending on the condition of the hair or skin of the user or on the preference of the user. In the above-described conventional shaver, it becomes necessary to change the spring force of the inner cutter upwardly pushing spring in order to change that float pressure. In order to weaken the outer cutter float pressure, for example, the inner cutter upwardly pushing spring may be made weaker. When that is done, however, the contact pressure between the inner cutter and the outer cutter will become weaker, and there will be a danger that the sharpness of the shave will deteriorate. In order to strengthen the outer cutter float pressure, conversely, the inner cutter upwardly pushing spring may be made stronger. When that is done, however, the contact pressure between the inner cutter and the outer cutter tends to become excessive, leading to such problems as the noise caused by sliding sounds becoming greater, or the temperature of the outer cutter surface rising due to the heat of friction.
In view of the above situations, the inventor of the present application studied a structure of elastically supporting the outer cutter in the up and down direction relative to the outer cutter frame, for the purpose of being able to set the float pressure while optimally maintaining the contact pressure between the outer cutter and the inner cutter. It was found preferable that the outer cutter float pressure be adjustable from the shaver main body side. When, however, in such an adjustable structure, an outer cutter frame and shaver main body linking mechanism, that is, a mechanism for transmitting the movement of a manipulator on the shaver main body side to the float pressure adjustment mechanism on the outer cutter frame side, becomes necessary, and the structure as a result becomes complex.